1 //===--- DebugInfoSupport.cpp -- Utils for debug info support ---*- C++ -*-===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // Utilities to preserve and parse debug info from LinkGraphs. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #include "llvm/ExecutionEngine/Orc/Debugging/DebugInfoSupport.h" 14 15 #include "llvm/Support/SmallVectorMemoryBuffer.h" 16 17 #define DEBUG_TYPE "orc" 18 19 using namespace llvm; 20 using namespace llvm::orc; 21 using namespace llvm::jitlink; 22 23 namespace { 24 static DenseSet<StringRef> DWARFSectionNames = { 25 #define HANDLE_DWARF_SECTION(ENUM_NAME, ELF_NAME, CMDLINE_NAME, OPTION) \ 26 StringRef(ELF_NAME), 27 #include "llvm/BinaryFormat/Dwarf.def" 28 #undef HANDLE_DWARF_SECTION 29 }; 30 31 // We might be able to drop relocations to symbols that do end up 32 // being pruned by the linker, but for now we just preserve all 33 static void preserveDWARFSection(LinkGraph &G, Section &Sec) { 34 DenseMap<Block *, Symbol *> Preserved; 35 for (auto Sym : Sec.symbols()) { 36 auto [It, Inserted] = Preserved.try_emplace(&Sym->getBlock()); 37 if (Inserted || Sym->isLive()) 38 It->second = Sym; 39 } 40 for (auto Block : Sec.blocks()) { 41 auto &PSym = Preserved[Block]; 42 if (!PSym) 43 PSym = &G.addAnonymousSymbol(*Block, 0, 0, false, true); 44 else if (!PSym->isLive()) 45 PSym->setLive(true); 46 } 47 } 48 49 static SmallVector<char, 0> getSectionData(Section &Sec) { 50 SmallVector<char, 0> SecData; 51 SmallVector<Block *, 8> SecBlocks(Sec.blocks().begin(), Sec.blocks().end()); 52 std::sort(SecBlocks.begin(), SecBlocks.end(), [](Block *LHS, Block *RHS) { 53 return LHS->getAddress() < RHS->getAddress(); 54 }); 55 // Convert back to what object file would have, one blob of section content 56 // Assumes all zerofill 57 // TODO handle alignment? 58 // TODO handle alignment offset? 59 for (auto *Block : SecBlocks) { 60 if (Block->isZeroFill()) 61 SecData.resize(SecData.size() + Block->getSize(), 0); 62 else 63 SecData.append(Block->getContent().begin(), Block->getContent().end()); 64 } 65 return SecData; 66 } 67 68 static void dumpDWARFContext(DWARFContext &DC) { 69 auto options = llvm::DIDumpOptions(); 70 options.DumpType &= ~DIDT_UUID; 71 options.DumpType &= ~(1 << DIDT_ID_DebugFrame); 72 LLVM_DEBUG(DC.dump(dbgs(), options)); 73 } 74 75 } // namespace 76 77 Error llvm::orc::preserveDebugSections(LinkGraph &G) { 78 if (!G.getTargetTriple().isOSBinFormatELF()) { 79 return make_error<StringError>( 80 "preserveDebugSections only supports ELF LinkGraphs!", 81 inconvertibleErrorCode()); 82 } 83 for (auto &Sec : G.sections()) { 84 if (DWARFSectionNames.count(Sec.getName())) { 85 LLVM_DEBUG(dbgs() << "Preserving DWARF section " << Sec.getName() 86 << "\n"); 87 preserveDWARFSection(G, Sec); 88 } 89 } 90 return Error::success(); 91 } 92 93 Expected<std::pair<std::unique_ptr<DWARFContext>, 94 StringMap<std::unique_ptr<MemoryBuffer>>>> 95 llvm::orc::createDWARFContext(LinkGraph &G) { 96 if (!G.getTargetTriple().isOSBinFormatELF()) { 97 return make_error<StringError>( 98 "createDWARFContext only supports ELF LinkGraphs!", 99 inconvertibleErrorCode()); 100 } 101 StringMap<std::unique_ptr<MemoryBuffer>> DWARFSectionData; 102 for (auto &Sec : G.sections()) { 103 if (DWARFSectionNames.count(Sec.getName())) { 104 auto SecData = getSectionData(Sec); 105 auto Name = Sec.getName(); 106 // DWARFContext expects the section name to not start with a dot 107 Name.consume_front("."); 108 LLVM_DEBUG(dbgs() << "Creating DWARFContext section " << Name 109 << " with size " << SecData.size() << "\n"); 110 DWARFSectionData[Name] = 111 std::make_unique<SmallVectorMemoryBuffer>(std::move(SecData)); 112 } 113 } 114 auto Ctx = 115 DWARFContext::create(DWARFSectionData, G.getPointerSize(), 116 G.getEndianness() == llvm::endianness::little); 117 dumpDWARFContext(*Ctx); 118 return std::make_pair(std::move(Ctx), std::move(DWARFSectionData)); 119 } 120